GMT’s Empire of the Sun is one of those games that always generates a lot of discussion. The game’s reputation is one of having a really steep learning curve, but being ultimately rewarding for those willing to put in the effort. The investment that has to go into learning such a game can often seem daunting and at times off putting for the uninitiated. I know when I sat down to read the rules book that I was quite intimidated just by the sheer size. So I’m going to try and put down some of the key concepts into easy, consumable pieces with lots of pictures to try and help those on the cusp of getting into the game feel a bit more confident and comfortable whilst playing this beast.


I can personally attest to the greatness of this game (you can read my introductory review to the game here). The sheer scale and open-endedness is something that elevates this game above so many others. Empire of the Sun is said to be Mark Herman’s masterpiece, and a masterpiece it surely is, but there’s some other games of his that you should check out if you’re feeling intimidated. No designer just pumps out the mechanics for a game like this over a weekend, rather there’s been years of experience brewing and culminating in this design. So, if you’re worried EotS is too much for you, go out and buy France 1944 – The Allied Crusade In Europe. It’s an older deign by Mark Herman but includes some very important mechanics that are built upon in EotS: Zones of Control, and the HQ activation system. Another game to check out is We The People, Mark Herman’s first Card Driven Game, where he birthed that system that has become so popular. You can become familiar with these mechanics in these less complex games, so that there will be some familiarity with them when you finally tackle Empire of the Sun, in which Herman culminated and refined these systems.

So, today’s discussion will be about the rules and concepts regarding Zones of Influence [hereafter referred to as ZOIs] because this is something that both makes the game and breaks the game [when you forget them]. New players often have a hard time with ZOIs because they are abstract and not marked on the board, you just have to know they’re there and visualize them. If it’s a real struggle for you, I recommend the Vassal Module because you can toggle them off and on as you learn and play around with them on there: a great tool.

What Is a Zone of Influence?

ZOIs are an area surrounding aircraft and aircraft carrier units that represents these units’ capacity to patrol and intercept enemies within their normal operating limits. In Empire of the Sun each and every air and carrier unit projects a 2-hex ZOI that has a number of game effects, some of which we’ll discuss here. Figure 1 below shows a few units on the board with their ZOIs marked. Again, that’s the hardest part of ZOIs is remembering and constantly looking for them and measuring them. I keep my air units and carriers on top of stacks so I don’t have to root through them in order to see if a stack even projects a ZOI.

Figure 1 – Air and carrier units all project a 2-hex ZOI

From Figure 1, the carrier Shokaku will move from hex 3813 down to hex 4019. As the carrier moves the ZOI moves with it, constantly being in effect. It does not turn off during the move and then activate again once finished moving. [NOTE – This is the case for strategic movement. During strategic movement aircraft and carriers do not project ZOIs, this represents a sacrifice of patrols and caution for the pragmatism of speed.] Having completed it’s move the Shokaku finds it’s ZOI overlapping with the ZOI of the allied air forces stationed at Admiralty Island (hex 3820). So what happens when opposing ZOIs overlap? For every hex in which opposing ZOIs overlap these hexes are ‘neutralized’ in terms of ZOIs.

Figure 2 – Overlapping Japanese and Allied ZOIs neutralize each other

The green area in Figure 2 shows the hexes in which the ZOIs are neutralized. This means that for almost all game purposes the ZOIs don’t cause negative impacts for the opposing player in those spaces. An example of which can be that now the shaded hexes can be used by units conducting strategic movement in subsequent move phases (but more about that later). This represents both sides running sorties and standing off from open conflict and therefore neither one side has air superiority.

How Can ZOIs be Utilized?

Figure 3 – Activating Central Pacific HQ has a command Range of 25.

So why are ZOIs even in the game? What functions do they perform? What can I as a player do with them? There’s a lot of other questions surrounding ZOIs, especially for newer players, because ZOIs are so integral and have unique and manifold functions in Empire of the Sun. Now we’re going to take a look at activation paths. For a unit to be activated, by the play of a card it needs to be within the command range of the activating HQ. In this example, the activating HQ is the Allied Central Pacific HQ located in Oahu, hex 5808 (Figure 3). C Pac. has a command range of 25, printed in the bottom right hand corner of the chit. This signifies that for a unit to be activated by C Pac. it must be able to count no more than 25 unobstructed hexes between itself and the HQ. This trace does not have to be a straight line, and more often than not you’ll find yourself tracing around enemy un-neutalized ZOIs.

In Figure 4 The New Orleans, an American cruiser, is stationed on the coast of New Guinea in hex 3720. The New Orleans is 23 hexes away from Central Pacific HQ, which is within the command range and therefore is eligible to be activated and also is in full supply.

Figure 4 – The Cruiser New Orleans can trace an unblocked activation path to Central Pacific HQ that is within the 25 hex command range of C. Pac.

With careful positioning the Japanese player moves some units to try and catch the New Orleans out of supply and to prevent it from being activated. Each of the carrier and aircraft units project ZOIs (Figure 5), through which activation paths cannot be traced if they would be traced through an ‘all water’ hexside. From a quick glance at that map, that’s a majority of the play space, so positioning is very important in Empire of the Sun. With some astute moves you can cut off enemies, or force them into fighting battles that are on your terms.

Figure 5 – Japanese air and naval units are moved to Kavieng and Truk, blocking the activation path with their ZOIs

Because the ZOIs of the Japanese units project across hexes with all water hexsides, activation cannot be traced through these hexes, shown in Figure 5 [This simulates that Japanese units are jamming communications and intercepting orders]. The Allied player would have to trace an activation path circumventing the Japanese ZOIs in order to be able to activate the New Orleans. Unfortunately for the Allies, Figure 6 shows that the Japanese player was very astute in their placement as tracing around either side of the ZOIs creates an activation path that is longer than 25 hexes. This puts the Cruiser ‘out of range’ for purposes of being activated by C. Pac. HQ. Furthermore The New Orleans is now Out of Supply, which has other game effects including being potentially susceptible to attrition.

Figure 6 – The allied player cannot trace activation (and therefore supply also) that is 25 hexes or less due to the interference of Japanese ZOIs. The Cruiser is out of supply and may not be activated.

Zones of Influence represent the brand new type of warfare that was forged in the Pacific Theatre of operations. Never before had air naval combat been conducted on such large scales. Being able to master placement of ZOIs to block supply and activation paths, as well as neutralizing key enemy ZOIs that would hurt your strategies is something that is very rewarding in Empire of the Sun. With so many of the units on the map projecting ZOIs that board quickly can become a maze of enemy units to try and navigate effectively.

Rules to Remember – Other ZOI Implications

Zones of Influence have a number of other game effects, that are more simple to illustrate and understand, but that are often forgotten and overlooked. There’s a lot of rules to remember whilst playing this game, and these few are ones that new players are susceptible to passing over (which can have major implications for the balance and flow of a game).

Firstly, any un-neautralized enemy Zone of Influence will block a ground unit from amphibious assault. Figure 7 shows the US 1M marine division attempting to land at Kwajalein (hex 4715). This is an illegal move, because Kwajalein is under an un-neutralized Japanese Zone of Influence. This rule forces historically representative combat, in that you as a player have to conduct air/naval combat before landing troops, else your marines would be shot to pieces in their landing crafts by enemy Zeros.

Figure 7 – Amphibious assualt into a hex containing an un-neutralized enemy ZOI is never allowed.

Secondly, when conducting an offensive, if any activated units move into or out of an enemy ZOI then the enemy [referred to as the ‘reaction player’] will receive a +2 die roll modifier when attempting to change the intelligence level of the offensive. NOTE – This modifier is incurred even if the ZOI has been neautralized! This signifies enemy reconnaissance in these areas, even if they are contested with opposing ZOIs, it’s hard to sneak a battle ship through a dog fight! Figure 8 illustrates this, the allied stack containing the Mississippi moves to attack hex 3319 (Biak) because the stack moves into the ZOI of the Japanese 23rd Air Flotilla the Japanese player will receive a +2 modifier to the intelligence changing die roll.

Figure 8 – Any offensive conducted into, or of, or through an enemy ZOI grants the reaction player a +2 DRM to change the intelligence level of the offensive.

Thirdly, units using Strategic movement may never enter enemy ZOIs. Units using strategic movement also do not project a ZOI whilst using strategic movement. This is the only case where this happens, units using regular movement have their ZOI constantly moving with them, affecting all hexes eligible as it moves.

And lastly, enemy ZOIs do not block command range, when determining the maintenance of reduced units for purposes of attrition. This seemingly odd exception to the rules represents High Command’s desire to keep reduced units from being lost to attrition and the daring supply missions that were conducted through hot waters to keep soldiers alive

So hopefully we’ve all learned something about Zones of Influence and that we can be a bit more comfortable at least with that aspect of the game. I know I’ve reinforced my personal knowledge of how things work just by writing this. If you have any questions feel free to ask away and I’ll do my best to answer them (eventually at least). Watch out for more of these entries in the series on our blog as we tackle other rules and concepts from Empire of the Sun.